---
id: "CVE-2026-126952"
page: "https://infrastack.ai/live/CVE-2026-126952"
kind: "vulnerability"
aliases: ["CVE-2026-126952"]
title: "Zipline: WebAuthn login accepts a credential ID, letting attackers impersonate users"
severity: "critical"
cvss: 9.2
epss: null
exploited: false
status: "open"
category: "package"
products: [{"name": "zipline", "fixed": ["4.4.1"], "affected": "<= 4.4.0", "ecosystem": "github"}]
ecosystems: []
tags: ["package", "passkeys", "self-hosted", "webauthn", "zipline"]
not_affected_if: ["no-registered-passkeys", "passkey-login-disabled"]
published_at: "2026-11-13T10:18:02+00:00"
first_seen_at: "2026-11-13T10:47:28+00:00"
updated_at: "2026-11-13T10:49:57+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-126952", "first_seen_at": "2026-11-13T10:47:28+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-11-13T10:49:57+00:00"}]
exploit_sources: []
---

# Zipline: WebAuthn login accepts a credential ID, letting attackers impersonate users

Link for people: https://infrastack.ai/live/CVE-2026-126952 (this .md is for agents)

Zipline, a self-hosted file sharing server, has a flaw in its WebAuthn (passkey) login endpoint that creates a session for any registered credential ID without checking the signed assertion. An attacker who learns a user's passkey credential ID can log in as that account and potentially gain SUPERADMIN control.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- github:zipline affected <= 4.4.0 fixed 4.4.1

## How to check

- Check the running Zipline version; v4.4.0 is the affected release per the GitHub advisory (VulnCheck says through 4.4.0).
- Check whether passkeys are enabled and whether any user has registered a passkey. The advisory says the bypass applies when passkeys are enabled; it does not state the default.
- An attacker needs the real credential ID of a passkey registered to the target account.

## Fix

Upgrade to Zipline v4.4.1 or later (current releases are 4.8.x). If you cannot upgrade, disable passkey authentication.

## Timeline

- 2026-11-13T10:47:28+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-126952
- 2026-11-13T10:49:57+00:00 analyst — Read GHSA-8g3f-425r-35rq and VulnCheck. Advisory header says Patched: None but text says fix is in v4.4.1; upgrade to v4.4.1 or later. Passkey default not stated. No PoC link, no exploitation reported.

## Documents

- [advisory] Vendor advisory: github.com https://github.com/diced/zipline/security/advisories/GHSA-8g3f-425r-35rq
- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/zipline-through-4.4.0-webauthn-authentication-bypass-via-passkey-login

## From the sources

Zipline through 4.4.0 contains an authentication bypass vulnerability in the WebAuthn login endpoint that creates sessions for a supplied registered credential ID without verifying the assertion. Attackers who obtain a target's passkey credential ID can impersonate that account without its authenticator, potentially gaining administrative control over SUPERADMIN accounts.

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_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_